It is believed generally in the industry that the backing must be "conductive", or must have a conductive substrate, in order that an electrostatic image may be produced, and this precept has delayed the introduction of materials which have not been rendered conductive.
One way in which paper is commonly rendered conductive is to make it hydrophilic which, of course, renders it unsatisfactory in the production of lithographic masters. A feature of paper backings is that the coatings produced on it by the present methods have a peculiar "feel" which is now well known and results in unfavorable comparisions with plain paper.